linux-kernel - Re: [PATCH v2] lib/test_printf.c: call wait_for_random

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Date:   Wed, 13 Jun 2018 16:59:27 +0200
From:   Thierry Escande <thierry.escande@...aro.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Miller <davem@...emloft.net>,
        Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] lib/test_printf.c: call wait_for_random_bytes() before
 plain %p tests

On 13/06/2018 13:22, Andy Shevchenko wrote:
> On Wed, Jun 13, 2018 at 12:29 PM, Thierry Escande
> <thierry.escande@...aro.org> wrote:
>> If the test_printf module is loaded before the crng is initialized, the
>> plain 'p' tests will fail because the printed address will not be hashed
>> and the buffer will contain "(ptrval)" instead.
>> Since we cannot wait for the crng to be initialized for an undefined
>> time, both plain 'p' tests now accept the string "(ptrval)" as a valid
>> result and print a warning message.
> 
> There are two possibilities:
>   1. (ptrval) for 32-bit case
>   2. (____ptrval____) for 64-bit case.

 From lib/vsprintf.c, ptr_to_id() puts "(ptrval)" into the buffer, then 
it gets left-padded with spaces by widen_string().

Regards,
Thierry